Method and apparatus for obtaining fluid samples from drilled wells



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May 12, ma

G. A. MACREADY METHOD AND APPARTUS FOR OBTAINING FLUID SAMPLES FROM DRILLED WELLS Filed July 50, 1954 Yah,

Y f 67 /l 6 Patented May 12, 1936 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR OBTAIN- ING FLUID SAMPLES FROM DRILLED WELLS George A. Macready, Los Angeles, Calif.

Application July 30, 1934, Serial No. 737,607

(C1. 16e- 1) v ple to obstruct upward flow of the sample, pre- 8 Claims.

My invention relates to bore holes or drilled wells in which it is desired to test formations or casing to determine the character of fluid they will yield.

My invention relates more particularly to improvements in single tube testers.

In the art of drilling wells for petroleum or other fluid products it is essential that undesirable fiuid such as water be excluded from the productive formations. The usual practice is to seal a string of steel casing to the Wall of the Well by cement so that all fluid originating from the formations above the seal is excluded from the interior of the casing and the desired fluid from below the cemented casing can then be drawn through the casing.

Most wells are now drilled by hydraulic methods and consequently are full of liquid during drilling so that it is diicult to identify the character of fiuid in the formations encountered during drilling. Since casing is expensive it is desirable to make a preliminary test of the formation before setting and cementing casing. It is also desirable to test the effectiveness of a cemented casing before drilling ahead. This can be done by taking a sample of fluid from the well with my invention.

In 1922 I invented a method and apparatus by which samples of fluid for the above purpose could be taken with the single string of drill pipe used in drilling the well and was granted Letters Patent Numbers 1,896,492 and 1,896,522 therefor. This application covers improvements over my original invention.

With my invention a seal is made by means of a packer between the foot of the drill pipe and the wall of the well above the formation to be tested, a sample of uid is drawn into the drill pipe, and the drill pipe removed from the Well with the sample entrapped therein.

An object of my invention is a single tube fluid sampler of simple construction economical to build.

An object of my invention is a method for testing wells by the use of a marker in the uid column to indicate the top of the fluid sample obtained in the drill pipe or sample tube.

An object of my invention is a method for taking fluid samples from drilled wells with a single string of pipe by temporarily sealing the string against the well Wall above the formation to be sampled, causing a sample of formation fluid to enter the pipe, positioning an identifiable marker in the pipe at the top of the sample, placing a-n obstruction in the pipe above the samventing downward escape of the sample from the pipe, and pulling the pipe from the well to deliver the sample at the top of thewell for inspection.

An object of my invention is a novel form of check or go-devil valve which can be dropped down the drill pipe to obstruct the upward flow of uid in the pipe.

An object of my invention is a novel form of valve which excludes uid from the drill pipe and which can be opened by dropping a weight thereon when ready to admit a sample. f

An object of my invention is a simple form of pressure relief to ease the load of fluid when raising the packer by first breaking a small seal and uncovering a relief port before the entire packer is raised thereby equalizing pressure on both sides of the packer.

An object of my invention is a simple method and apparatus for testing the effectiveness of the cement seal or Water-shut-off by which a string of casing excludes water from an oil formation.

With the foregoing and other objects in view which will be made manifest in the following detailed description and especially pointed out in the appended claims, reference is had to the accompanying drawing for illustrative embodiment of my invention, wherein;-

Figure 1 is a longitudinal section of the packer, valve and release port attached to the lower end of a string of drill pipe with valve closed as it is when lowered into a well,

Figure 2 is a longitudinal section showing a packer seated and the valve open to admit a uid sample,

Figure 3 in its upper portion shows a section of the drill pipe with the go-devil check valve seated and in its lower portion shows an external View of the packer and valve case on the way out of the well with a fluid sample,

Figure 4 is a cross-section at 4--4 in Figure 1,

Figure 5 is a longitudinal section of a cased well with an external View of a tester therein having a hook wall packer for testing the effectiveness of a casing Water-shut-off.

Similar numerals refer to similar parts throughout the several views.

In the accompanying drawing Figure 1 shows an assembly attached to the foot of the drill pipe I by the tool joint 2 for making a test of formation penetrated by a rat hole 5|. The assembly consists of a valve case 3 and packer 4 described more in detail as follows: l

'I'he packer 4 is mounted about a central tube 5 attached as by screw threads 6 to the lower end of case 3. The packer 4 is slightly shorter than the distance between case 3 and shoulder 'I so that it can slide longitudinally a short distance along tube 5 covering or uncovering ports 9 through the wall of tube 5. A perforated pipe or extension B extends below the packer as a gathering tube to admit the fluid sample. The packer 4 may be moulded as a single block of rubber, lead or otherdeformable substance or it may be made of multiple pieces such as discs of belting.

The valve cage 3 has an internal chamber I open at the upper end to the drill pipe and at the lower end having a valve seat inlet II communicating with tube 5. A ball valve I2 forms a check valve closure for inlet I I. Normally ball valve I2 seats against inlet I I to prevent escape of fluid from the drill pipe but opens to admit fluid into the drill pipe.

In lowering the assembly into a well to take a fluid sample the ball valve I2 is locked against inlet II by a releasable lock to prevent flow in either direction until unlocked. vThe locking mechanism is as follows: A rod I3 and rocker arm I4 are pivoted to a yoke or cross I5. Rod I3 is pivoted at I'I to plate I 6 and arm I4 is attached to plate I6 by toggle piece I8. By screwing ring I9 down on yoke I5 with toggle piece I8 and arm I4 in the positions illustrated in Figure 1 the ball valve I2 is clamped against inlet II to close the inlet.

When it is desired to unlock valve I2 a weight 20 is dropped down the drill pipe to strike the target I4.of rocker arm I4 and kick the toggle piece I8 into the position illustrated in Figure 2 thus releasing plate I6 from ball I2.

In the upper portion of Figure 3 is shown a novel go-devil check valve which is dropped into the drill pipe to obstruct upward flow of fluid through the drill pipe. The usual practice in rotary well drilling is to connect the sections of pipe together by means of tool joints provided with coarse threads of blunt taper that can be quickly unscrewed. The pin or male thread end is usually on the lower end of each section of pipe and is of small bore thus forming a shoulder on the interior wall ofthe pipe.

The go-devil check valve consists of a rod 2l rounded at the lower end and provided with the conventional spring guides 22, 23 to guide it through the tool joints. A coupling 24 is rigidly attached to the upper end of rod 2I and an end piece 25 attached. A closure member 28 of rubber or other deformable material is retained about piece 25 between shoulders 26 and 2I. The upper end of member 28 is flared at 29 so as to be normally larger than the diameter of the tool joint bore but with springiness so that it can bend back to permit the go-devil to drop through the tool joints. This form has the effect of an annular barb. Parts 24 and 25 may be of aluminum and rod 2| of wood so that the specic gravity of the entire go-devil is less than water and it will float on the top of the mud fluid in the drill pipe.

In operation the go-devil valve is dropped down the drill pipe. Being lighter in weight than the mud fluid it stops at the top of the mud fluid or liquid in the drill pipe and oats thereon. If the liquid is flowing upward in the drill pipe the godevil valve oats upward thereon until it contacts the pin of a tool joint 30. 'Iip 25 centers the valve in the bore of the tool joint but the flared end 29 of. member 23 acts as an annular barb and is stopped at the shoulder on the end I the tool joint pin and spreads to further resist upward movement of the go-devil to cause deformable member 28 to pack and expand closing the bore of the tool joint and obstructing upward ilow of iluid through the drill pipe.

For taking samples in an uncased hole it has been found most satisfactory to reduce the diameter of the well bore so that a shoulder is formed at the top of the reduced bore or rat hole and to make the seal by means of a tapered packer 4 pressed against the shoulder by weight of the drill pipe as illustrated in Figure 2. 'I'he rat hole shoulder should be concentric with the larger hole in order to have a complete annular sealing shoulder.

For testing the eifectiveness of the seal of a cemented string of casing a rat hole shoulder is diflicult to form but the smooth surface of the casing is readily adapted to use of a hook wall packer. Figure illustrates an assembly for testing a casing 38 cemented at 39. Valve case 36 is the same as the one previously described for the rat hole tests and is attached to the foot of drill pipe string 3l. Instead of the tapered rat hole packer the hook wall packer is used. Bow springs 45 are mounted about central tube 4I and held in position during lowering by pin 42 in hook slot 43. When tube 4I is turned to the right by the drill pipe it can be lowered through the bow springs because pin 42 can descend in slot 43. Slips 44 remain stationary supported by friction of the bow springs on the casing and cone 45 Spreads them to grip the casing. Packing 4S is then expanded between descending cone 4'I and stationary cone 45 to seal between casing 38 and valve casing 36. Relief port 48 is also closed by descent of tube 4I through cone 41.

In some wells it may be advantageous to establish mud iluid circulation through the drill pipe to prevent the drill pipe becoming stuck so for this purpose the emergency side check valves 68 may be provided. In order not to lose the sample through the side check valves the springs holding them on their seats should be strong enough to resist opening against considerable pressure but should be free to open when circulation pressure of several hundred pounds per square inch is applied. The side check valves are an emergency protection which can be omitted except in treacherous wells.

In order to take samples of formation fluid with the apparatus above described the following system or procedure should be followed:

In uncased wells a shoulder 5B should be prepared on the wall of the well by drilling a hole of smaller diameter 5I below the hole of full diameter 52 and into the formation to be tested 53. It is preferable to have the shoulder on firm impervious formation such as shale.

In `cased wells where it is desired to test the eifectiveness of a cement seal illustrated in Figure 5 the cement is drilled through as at 54 and the shoulder 45 is lowered in with the sampling apparatus, as part of the hook wall packer.

In some uncased wells having rm smooth walls the test may be made with the hook wall packer instead of the rat hole packer,

The sampling apparatus illustrated in Figure 1 for rat hole tests or in Figure 5 for casing tests is attached to the foot of the drill pipe and lowered into the well with the ball valve I2 held closed over the inlet I I by the plate I5 so that no fluid is allowed to enter the drill pipe through the inlet. As an identifying marker for the top of Cil ` or 41 and the bottom of valve case 3 or 36.

the fluid sample a short length 55 of identifiable liquid such as white-wash may be poured into the drill pipe either before or after the sample has been admitted to the drill pipe.

At the desired level for making the seal the packer is compressed between shoulder 50 and valve case 3 for rat hole tests or between cone 45 and valve case 36 for casing tests by applying weight of the drill pipe so that an impervious water-shut-off or barrier seal is formed between the wall of the well and valve inlet II to exclude fluid in the well above the seal from the interior of the drill pipe.

After the well is sealed to form a water-shutoff a weight 20 is dropped through the drill pipe to strike target I4a of rocker arm I4 and tilt toggle piece I8 into the position illustrated in Figure 2 lifting plate I6 olf ball valve I2 and opening inlet II. A sample 56 of fluid from the well below the seal is now free to enter the drill v pushing the marker fluid 55 ahead of it to position 55a.

When the weight 20 is dropped into the drill pipe it is advisable to observe the uid level on the outside of the drill pipe. If the fluid level on the outside of the drill pipe falls when weight 20 trips the valve it is evidence that the seal at shoulder 5|) or 45 is not effective and the upward flow of liquid in the drill pipe should be stopped as provided in the following paragraph.

When suicient sample has been admitted to the drill pipe or it is desired to stop the upward ow of fluid therein the drill pipe may be pumped full of fluid from the upper end to balance and obstruct the upflow; or, the go-devil check valve ilustrated in the upper part of Figure 3 may be dropped into the drill pipe at its upper end.

The drill pipe is next raised to break the "watershutoff seal. If the liuid pressure below the seal is low the hydrostatic column of mud uid in the well outside the drill pipe holds the packer on its seat with great force. The hydrostatic load on a large packer at great depth may be so heavy that the drill pipe may part or break before lifting the packer from its seat. To relieve this load a secondary seal 51, 58 of small diameter is provided between the packer 4 As illustrated in the drawing provision is made for a short longitudinal movement of the packer along tube 5 or 4I The diameter of the annular seal 51, 58 is smaller than the drill pipe and only slightly larger than tube 5 or 4I so that the pull on the drill pipe required to break the seal is not excessive. Therefore, when the drill pipe is raised seal 51 or 58 is broken first and tube 5 or 4I is drawn up through the packer uncovering ports 9 or 48. Fluid from around the drill pipe immediately rushes in through ports 9, 48 and tube 5, 4I into the well below the packer thus equalizing the pressure on both sides of the packer 4, 41 and relieving the hydrostatic load thereon so that the packer can easily be lifted oi its seat.

If the level of liquid within is below the level of liquid outside the drill pipe then part of the fluid entering through the relief ports passes through inlet II into the drill pipe pushing the sample and marker liquids upward therein.

The go-devil check valve being constructed light to float on liquid is floatedupward with the rising liquid column until it engages a tool joint as illustrated in Figure 3. The top of the go-devil check valve is guided and centered in the bore of the tool joint pin but the flared end f .il

or annular barb 29 of deformable member 28 is stopped by the shoulder at the end of the tool joint pin. Pressure from the rising liquid column spreads the annular barb and expands the rear portion of deformable member 28 to completely y5 obstruct the bore of the tool joint and stop upward travel of liquid through the drill pipe.

It may be mentioned here that the use of the go-devil check valve necessitates the presence of shoulders on the interior wall of the pipe against 10 which the go-devil can seal. Suitable shoulders occur about forty feet apart on the rotary drill pipe used in usual drilling practice. The godevil seal is made at a tool joint where it is customary to disconnect the pipe so that there 15 is no .difficulty in recovering the go-devil for future use. If suitable shoulders do not occur in the test pipe then mud fluid can be pumped in through the top of the drill pipe to obstruct upward ow therein. Mud fluid is not so pleasant 20 because it splashes over the crew when the pipe is pulled from the well.

At this stage of proceedings the drill pipe contains a short length of drilling mud fluid 59 in its lower portion, the sample of formation 25 fluid 561) above the drilling mud, an identifiable marker above the sample consisting of either the identifiable fluid 55h or the go-devil check valve floating above the sample or both, and an obstruction in the drill pipe above the sample consisting of either the 'mud fluid pumped in from the top of the drill pipe to balance the liquid column or the deformable member 28 of the godevil valve lodged against a tool joint, the obstruction in either form being to prevent upward flow. The sample is securely trappe-d being prevented from escaping downward by check valve I2 and upward escape by the obstruction.

The drill pipe is pulled out of the well with the sample of formation fluid entrapped therein 40' so that the sample is delivered at the top of the well for inspection.

After a test has been made and it is desired to set ball valve I2 for another test the weight 29 is removed, ring I9 is backed off by unscrew- 45 ing, arm I4 and toggle piece I8 are pushed over to the position illustrated in Figure 1, ball I2 is allowed to roll onto its seat closing inlet II, and ring I9 is screwed down tight to clamp ball valve I2 on inlet II. Notch/es 62 can be pro- 50 vided in ring Il to receive a wrench.

It will be understood that various changes in detail of construction may be made Without departing from the spirit and scope of the invention as defined by the appended claims.

I claim as my invention:

1. A method for obtaining samples from drilled wells with a single string of pipe which consists of lowering said pipe into a well, said pipe being closed against entry of fluid from the Well 60 during lowering, temporarily sealing the lower end of said pipe to the wall of the well above that portion of the well to be sampled so as to exclude iiuid in the well above the seal from entering said pipe, opening the lower end of said 65 pipe to admit a sample of fluid from below said seal into said pipe, there being a check valve in the lower end of said pipe closing said pipe against escape of said sample and trapping said l sample inside said pipe, positioning an identifl- .02

able marker in said pipe adjacent the upper poriffjx tion of said sample to identify the top of said sample, placing an obstruction in said pipe above the liquid portion of said sample to obstruct upward now wil-,hm said pipe, breaking the tem- 75 porary seal, and pulling the string of pipe from the well with said sample entrapped therein to deliver said sample at the top of said well for inspection.

2. A method for obtaining samples from drilled wells with a single string of pipe which consists of lowering said pipe into a well, said pipe be ing closed against entry of iiuid from the well during lowering, temporarily sealing the lower end of said pipe to the wall of the well above that portion of the well to be sampled so as to exclude fluid in the well above the seal from entering sai-d pipe, opening the lower end of said pipe to admit a sample of fluid from below said seal into said pipe, there being a check valve in the lower end of said pipe closing said pipe against escape of said sample and trapping said sample inside said pipe, placing an obstruction in said pipe above the liquid portion of said sample to obstruct upward flow within said pipe, breaking the temporary seal, and pulling the string of pipe from the well with said sample entrapped therein to deliver said sample at the top of said well for inspection.

3. A go-devil check valve adapted to be dropped down a string of pipe to the liquid therein comprising a rod and an annular barb of deformable material mounted on said rod and adapted to engage a shoulder on the interior wall of said pipe when said valve is floated upward by rising liquid therein, said valve having a specic gravity less than said liquid to float thereon and said bar being deformable to obstruct upward flow of uid in said pipe when in engagement with said shoulder.

4. A packer for Wells consisting of a connecting member adapted to be attached to the lower end of a string of pipe provided with a central longitudinal passage therethrough and having an annular surface about said passageway at the end opposite the pipe connection, a tube of smaller diameter than said member attached to said member in communication with said passage and provided with a lateral relief perforation adjacent said annular surface, and a deformable packing member adapted to seal against the wall of a Well slidably mounted about said tube with limited longitudinal movement su'icient to cover and uncover said relief perforation, said packing member being provided with an annular end surface adapted to contact the annular surface on the connecting member to form an annular liquid tight seal about said tube when weight from the connecting member is applied to the packing member, the seal between the packing and connecting members being'of smaller diameter than.l the seal between the packing member and the well wall.

5. A go-devil check Valve for use in wells comprising a rod and an annular barb of deformable material mounted thereon.

6. An apparatus for obtaining samples from drilled wells comprising a string of pipe, a valve on the lower end of said pipe, a lock for locking said valve in closed position, said lock being unlocked by dropping a weight thereon, a perforated pipe attached below said valve and provided with -annular shoulders thereon, a packer slidably mounted about said perforated pipe between said shoulders and adapted to cover and uncover said perforations, and a go-devil check valve adapted to be dropped through said string of pipe to engage the interior wall of said string to close against upward flow of fluid through said string of pipe.

7. A valve comprising a case provided with an inlet at the lower end thereof, a closure member in said case adapted to seat over and close said inlet, a piece adapted to engage said closure member to press said member on its seat, a clamp ring within said case in threaded engagement with said case, a toggle joint between said piece and said clamp ring adapted to transmit pressure from said clamp ring to press said closure member on its seat, and an arm provided with a target by which said toggle is disengaged to release the pressure on said closure when pressure is applied to the target of said arm.

8. A go-devil check valve for use in wells comprising a rod, a barb on said rod, and sealing material on said rod adapted to engage the interior wall of a tube to obstruct ilow of liquid through said tube.

GEORGE A. MACREADY. 

